There is considerable diversity in the classes of drugs under investigation, and also the diseases which are targeted by this group. Nonetheless, the primary focus is always on the application of pharmacokinetic principles to questions of relevance to the treatment of cancer. Over the last year, specific areas of interest included: 1. Relationships between in vitro pharmacology and clinical trials targeted against HTLV-III/AIDS. Matching of in vitro and in vivo exposure conditions, determination of clinical pharmacokinetics of suramin, and application of kinetic analysis to suggest improved schedules of administration. 2. Although intramural clinical resources are limited, Phase I trials of new agents remain as an important element in a balanced approach to the clinical pharmacology of anticancer drugs. Trials were completed for spiromustine and tiazofurin, and started for trimetrexate. 3. In collaboration with the Radiation Oncology Branch, work has shifted from the use of BUdR to IUdR, with specific focus on the manipulation of intracellular pharmacology. 4. Pharmacokinetic evaluation of established agents. Studies of cisplatin and 5-fluorouracil were completed, while work begun on thio-TEPA.